When most people get their DEXA results, they look for one number, the T-score, and try to figure out whether it puts them in the osteopenia or osteoporosis range. If your report stopped there a few years ago, that was reasonable. Today, many modern DEXA reports include two additional pieces of information that can meaningfully change a treatment decision: Trabecular Bone Score (TBS) and Vertebral Fracture Assessment (VFA). They look like extras, but in the right patient they are not extras at all. They are the parts of the report that sometimes flip the answer.
I want to walk you through what each one is, when it matters, and what to ask your doctor if your report includes them.
A Quick Refresher on the T-Score
Your T-score compares the amount of mineral in your bone to a healthy young adult reference. It is a measure of quantity. What it cannot tell you is whether the bone you have is well organized internally, or whether you have already had a small vertebral fracture that you did not feel. Two people with identical T-scores can have very different real-world fracture risk, and the rest of the DEXA report is where that difference shows up.
What Is Trabecular Bone Score (TBS)?
Trabecular Bone Score is a measurement of bone quality, derived from the same lumbar spine images that produce your spine T-score. The software analyzes the subtle gray-scale variations in the image to estimate how well organized the inner, sponge-like (trabecular) bone is. A more uniform, finely textured pattern produces a higher TBS. A coarser pattern, where the internal struts have thinned and disconnected, produces a lower TBS (PMC review of TBS clinical performance, 2025).
TBS is usually reported as one of three categories:
- Normal: TBS above about 1.31
- Partially degraded: TBS roughly 1.23 to 1.31
- Degraded: TBS below about 1.23
The key point is that TBS predicts fractures independently of your T-score. Someone in the osteopenia range with a degraded TBS can have a higher real-world fracture risk than someone formally in the osteoporosis range with a normal TBS. That is not a paradox. It is what happens when you measure two different aspects of bone instead of one.
How TBS Changes a Treatment Decision
The 2023 International Society for Clinical Densitometry positions are explicit: TBS is appropriate for adults 40 and older, and it is most likely to change clinical management when you are close to a treatment threshold (ISCD 2023 Official Positions). In practice this means TBS most often helps in three situations:
- You are in the osteopenia range and your FRAX risk is close to the line where treatment is recommended.
- You have a condition known to weaken bone quality more than bone density, such as type 2 diabetes, primary hyperparathyroidism, chronic kidney disease, rheumatoid arthritis, or long-term glucocorticoid use (ABC of TBS, OFNM).
- Your spine T-score is artificially inflated by arthritis or calcifications and you want a measure of spine bone that those changes do not contaminate.
When TBS is added to FRAX as an adjustment, your ten-year fracture probability can shift up or down enough to change whether a medication is offered (ISCD 2023 TBS position, ScienceDirect). The TBS adjustment is available both on the standard FRAX website and through the newer FRAXplus tool, which combines TBS with other adjustments such as recent falls, glucocorticoid dose, and type 2 diabetes (FRAXplus adjustments overview, 2023). FRAXplus is still relatively new, and not every clinician has used it yet, so it is reasonable to mention it by name. If your DEXA report includes a TBS value but not a TBS-adjusted FRAX, that is a fair thing to ask for.
What Is Vertebral Fracture Assessment (VFA)?
Vertebral Fracture Assessment is a side-view image of your spine taken on the DEXA machine at the time of your scan. It is a low-radiation way to look directly at the vertebrae and check for fractures that have already happened, often silently.
This matters more than it sounds. Most vertebral fractures are not diagnosed when they occur. Estimates from population studies suggest that roughly two-thirds of vertebral compression fractures go undetected, because the back pain is mild, or attributed to a strain, or there is no pain at all (Vertebral fracture epidemiology and DXA-based VFA, PMC). And yet a single vertebral fracture, even a small wedge nobody noticed, is one of the strongest predictors that another fracture is coming.
The 2023 ISCD guidelines recommend VFA when the T-score is below -1.0 plus at least one of the following risk factors (Age and Ageing summary of ISCD VFA criteria, 2024):
- Women age 70 or older, or men age 80 or older
- Historical height loss of more than 4 cm (about 1.5 inches) from peak
- A self-reported but undocumented prior vertebral fracture
- Regular use of oral glucocorticoids
If a VFA shows even one previously unrecognized vertebral fracture, your diagnosis moves to established osteoporosis regardless of T-score, and that almost always triggers a recommendation for pharmacologic treatment.
How These Tools Fit Together
Think of your DEXA report as answering three different questions about your bones.
- T-score asks: how much bone do I have?
- TBS asks: how well organized is the bone I have?
- VFA asks: has my spine already shown signs of damage?
You can have a reassuring answer to one of those and a worrying answer to another, and the worrying one is often what should drive the plan. A patient with osteopenia by T-score, a degraded TBS, and a small wedge fracture on VFA is not a "borderline" case. That is high-risk osteoporosis hiding in plain sight, and the treatment conversation should look very different than it would based on the T-score alone.
What to Ask at Your Next Appointment
- Does my DEXA report include a TBS value, and if so, what is the number and category?
- Was a TBS-adjusted FRAX calculated, and does it change my ten-year fracture risk? Could we run my numbers through FRAXplus to factor in falls, steroid use, or diabetes as well?
- Do I meet the criteria for a VFA, and if so, was one done at my last scan or should one be added next time?
- If I have a known risk factor like diabetes or steroid use, are we factoring bone quality into my plan and not only bone density?
- Have I lost height since my peak adult height, and should that prompt additional imaging?
A Word About What You See on the Page
Not every facility reports TBS or VFA yet. The software for TBS is an add-on, and VFA requires the technologist to capture the lateral image, which adds a few minutes to the appointment. If your report does not include them and your situation suggests they would help, it is reasonable to ask whether a facility nearby offers them, or whether your scan images can be reanalyzed.
The reason I keep coming back to these two measures is that they answer the question patients actually care about, which is not "what is my T-score" but "what is my fracture risk, and what should I do about it." T-score is a piece of that answer. TBS and VFA, when they are available, often turn out to be the piece that decides.